1. Technical Field
The present invention relates generally to electric arc furnaces of the type typically used in the initial or reheat operations in the production of a metal, such as steel. In particular, the present invention relates to a method and apparatus for determining an amount of carbon electrode that is consumed during the production of a particular heat of the metal.
2. Description of the Prior Art
Carbon electrodes are typically used for applying electrical power to melt or reheat a charge contained in a furnace or ladle to produce a steel alloy of a certain chemical makeup or "chemistry". The carbon content in a steel alloy heat is very important. Often, however, the carbon of the electrode wears or is consumed during a heat at a rate that was not predicted or desired for a given steel alloy heat of a specified carbon content. When the resultant carbon content of the steel alloy heat is outside, usually above, the specified range for a given steel being produced, it must be scrapped or otherwise disposed of. Such disposal may take the form of further processing by making it into a steel of a "chemistry" that may not have an immediate market but is nonetheless useable.
An excessive carbon electrode consumption condition also occurs when, for example, the carbon electrode breaks and falls into the furnace to mix with the charge. Another way that the carbon electrode is consumed at an undesired or nonpredicted way is when a "butt joint" region in the electrode is encountered at an arc generating portion of the electrode. The butt joint region is typically consumed at a faster rate than normally would be consumed in a non-butt joint region of the electrode. However, excessive carbon electrode consumption most typically occurs during a normal reheating process, such as during ladle refining of a charge. The excessive consumption has varying magnitude depending on variables such as steel and slag chemistries or slag thickness.
Thus, a need exists for an apparatus and/or method that is able to predict when an excess carbon electrode consumption condition can exist during a heat and provides a way to enable or take corrective action when the excess consumption condition exists to prevent scrapping of a particular steel alloy heat or the need for further corrective processing.